The TCP/IP protocol suite, which is used for communication on the Internet, contains four abstraction layers: The hardware link layer, the routing network layer, the data flow handling transport layer, and the program specific application layer.
Variations in available bandwidth between two communicating hosts on a network, plays a role when transferring real-time information. The information quality may have to be adjusted according to the available data transfer rate.
Packets sent may be intended for a single recipient (unicast), or several recipients (multicast). Using multicast instead of sending the same packets to several hosts with unicasting, may save bandwidth. Multicasting between physically separated networks require special routers, most of which are currently implemented in software. The MBone is a multicasting network on top of the Internet.
Video may be transferred using general data transfer protocols, such as FTP and HTTP. To be able to play real-time while transferring, one needs protocols capable of adjusting the data stream according to the available bandwidth. Most existing protocols are currently not fully standardized.